A new note was published on M&M Heroes VII dev blog, and it concern background and History.
Futures players can discover, even they knew it, the Tales of The Ten Years War, starting at 843 YSD.
The narrator gives all story's details and explains the curse of Falcon and Griffin's royal family.

if you are interested about reading this story, you can find it on Heroes VII dev blog, or a tiny part below:

Many of you have approached me, asking to recount the events of the last ten years. I’m beginning to understand that many outside of the Holy Empire didn’t quite understand what was going on within our borders. As much pain as it causes me to recall the tragic events of this last decade, it is necessary if we are to bring an end to the bloodshed. This might take some time though. A lot happens in ten years, especially ten years of war.

But is the story I will tell you the truth? It would be presumptuous of me to say. I can only tell things as I saw them – my truth. Ask one of Seamus of Stag’s advisors and he might spin a widely different tale.